The present invention relates to cementing operations, and more particularly in certain embodiments, to the application of an oil-swellable particle to foamed cement compositions, and methods of using such compositions in surface and subterranean applications.
Cement compositions are commonly utilized above ground (e.g., in the construction industry) and in subterranean operations, particularly subterranean well completion and remedial operations. For example, cement compositions are used in primary cementing operations whereby pipe strings such as casings and liners may be cemented in well bores. In performing primary cementing, hydraulic cement compositions may be pumped into the annular space between the walls of a well bore and the exterior surface of the pipe string disposed therein. The cement composition is permitted to set in the annular space, thereby forming an annular sheath of hardened substantially impermeable cement therein that substantially supports and positions the pipe string in the well bore and bonds the exterior surface of the pipe string to the walls of the well bore. Cement compositions also may be used in remedial cementing operations such as plugging highly permeable zones or fractures in well bores, plugging cracks and holes in pipe strings, and the like.
Cement compositions utilized in subterranean operations may be lightweight to prevent excessive hydrostatic pressure from being exerted on subterranean formations penetrated by the well bore, whereby the formations may be unintentionally fractured. One type of lightweight cement composition is a foamed cement composition, i.e., a cement composition that comprises a gas and a foaming surfactant. In addition to being lightweight, the gas contained in the foamed cement composition may improve the ability of the composition to maintain pressure and prevent the flow of formation fluids into and through the cement composition during its transition time, i.e., the time during which the cement composition changes from a true fluid to a set mass. Foamed cement compositions may be advantageous because they can have low fluid loss properties and may act to prevent the loss of fluid during circulation. Additionally, foamed cement compositions when set should have a lower modulus of elasticity than non-foamed cements, which is often desirable as it enables the resultant set cement, inter alia, to resist hoop stresses exerted on the set cement in the annulus.
Once set, the cement sheath may be subjected to a variety of cyclic, shear, tensile, impact, flexural, and/or compressive stresses that may lead to failure of the cement sheath. Such failure may be the result of fractures, cracks, and/or debonding of the cement sheath from the pipe string and/or the formation. Undesirably, cement-sheath failure may lead to loss of zonal isolation, resulting, for example, in the undesirable migration of fluids between formation zones. This may lead to undesirable consequences such as lost production, costly remedial operations, environmental pollution, hazardous rig operations resulting from unexpected fluid flow from the formation caused by the loss of zonal isolation, and/or hazardous production operations. Furthermore, failure of the cement sheath also may be caused by forces exerted by shifts in subterranean formations surrounding the well bore, cement erosion, and repeated impacts from the drill bit and the drill pipe.